Watts to kWh calculator
Convert a power rating in watts, run for a given time, into the energy used in kilowatt-hours — the unit your electricity bill uses.
Result
Energy used
How to use this calculator
- Enter the power rating in watts.
- Enter how long it runs, in hours.
- Read the energy used in kWh.
Assumptions
- Assumes constant power draw for the full duration entered.
Technical details: what the fields mean
- Power
powerWatts - Power rating in watts, from an appliance's label or manual.
- Duration
hours - How long the appliance runs for, in hours.
Methodology
Energy (kWh) = power (W) ÷ 1000 × hours.
Worked example
2000W for 3 hours
Inputs: powerWatts=2000, hours=3
Result: 6.000 kWh
Practical guidance
- Use this alongside the kWh cost calculator to turn a device's wattage and run time directly into a cost.
Common mistakes
- Forgetting to convert watts to kilowatts (÷1000) before multiplying by hours — this calculator does that step for you.
FAQs
How do I convert watts to kWh?
Divide the wattage by 1000 to get kW, then multiply by the number of hours it runs.